Claire Beneteau

Delineation of 15q13.3 microdeletions

Masurel‐Paulet A, Andrieux J, Callier P, Cuisset JM, Le Caignec C, Holder M, Thauvin‐Robinet C, Doray B, Flori E, Alex‐Cordier MP, Beri M, Boute O, Delobel B, Dieux A, Vallee L, Jaillard S, Odent S, Isidor B, Beneteau C, Vigneron J, Bilan F, Gilbert‐Dussardier B, Dubourg C, Labalme A, Gautier A, Pernes P, Bidon C, Pinoit JM, Huet F, Mugneret F, Aral B, Jonveaux P, Sanlaville D, Faivre L. Delineation of 15q13.3 microdeletions.

SOS1 and PTPN11 mutations in five cases of Noonan syndrome with multiple giant cell lesions.

We report five cases of multiple giant cell lesions in patients with typical Noonan syndrome. Such association has frequently been referred to as Noonan-like/multiple giant cell (NL/MGCL) syndrome before the molecular definition of Noonan syndrome. Two patients show mutations in PTPN11 (p.Tyr62Asp and p.Asn308Asp) and three in SOS1 (p.Arg552Ser and p.Arg552Thr). The latter are the first SOS1 mutations reported outside PTPN11 in NL/MGCL syndrome. MGCL lesions were observed in jaws (‘cherubism’) and joints (‘pigmented villonodular synovitis’). We show through those patients that both types of MGCL are not PTPN11-specific, but rather represent a low penetrant (or perhaps overlooked) complication of the dysregulated RAS/MAPK signaling pathway. We recommend discarding NL/MGCL syndrome from the nosology, as this presentation is neither gene-nor allele-specific of Noonan syndrome; these patients should be described as Noonan syndrome with MGCL (of the mandible, the long bone…). The term cherubism should be used only when multiple giant cell lesions occur without any other clinical and molecular evidence of Noonan syndrome, with or without mutations of the SH3BP2 gene.

Recurrent mutation in the PIEZO1 gene in two families of hereditary xerocytosis with fetal hydrops

Fig. 1. (a) Pedigrees of the two families with hereditary xerocytosis (HX). The pedigrees show cosegregation of the HX phenotype and heterozygous mutation in PIEZO1 . +/+, patients with wild-type alleles; +/−, patients with heterozygous mutation. Not available (NA) indicates that biochemical and genetic analyzes are not available. No hyperkalemia, no gallstones were diagnosed in any members of the two families. (b) Hematological analyzes of patients with HX. At left, erythrocytes morphology showing target and hyperchromic cells with rare stomatocytes. At right, eosin5-maleimide (EMA) staining in flow cytometry showing increased fixation of the stain (black peak). (c) Sequence chromatogram showing the mutation found in the two families. At the top, sequencing data from an affected individual (III-5 of family 1), representing the normal and the mutant PIEZO1 alleles. A G->A transition changes the codon for arginine (CGC) in position 2456 of the PIEZO1 protein to the codon for histidine (CAC).

Clinical and molecular characterization of a large family with an interstitial 15q11q13 duplication

The clinical significance of an interstitial duplication of chromosome 15q11q13 is still not well documented. This abnormality has been associated with autistic spectrum disorders (ASD) and varying degrees of mental retardation. The clinical variability appears to be influenced by the parental origin of the duplication. We present here the clinical evaluation and psychological assessment of the largest reported family with 12 carriers on three generations. Patients exhibit mental retardation, motor and visuo‐motor skills impairments and adaptive functioning deficit without formal diagnosis of autism. There appeared to be evidence in the family of reduced penetrance in duplication of paternal origin. This familial 15q11q13 duplication was precisely investigated by cytogenetic and molecular techniques including fluorescence in situ hybridization (FISH), PCR analysis of microsatellite markers, array‐comparative genomic hybridization analysis (Array‐CGH) and semi‐quantitative methylation‐sensitive PCR. Results showed an inherited 15q11q13 duplication of maternal origin in 10 patients and of paternal origin in the remaining two. The size of the duplicated area was around 6 Mb with breakpoints in accordance with those previously reported. This report extends the clinical spectrum of the 15q11q13 duplication, and we recommend the investigation of 15q11q13 duplication not only in subjects with autistic spectrum disorder but also in patients with low normal intelligence and dyspraxia.

Multiple capillary skin malformations, epilepsy, microcephaly, mental retardation, hypoplasia of the distal phalanges: Report of a new case and further delineation of a new syndrome†

Multiple Capillary Skin Malformations, Epilepsy, Microcephaly, Mental Retardation, Hypoplasia of the Distal Phalanges: Report of a New Case and Further Delineation of a New Syndrome Bertrand Isidor,* S ebastien Barbarot, Claire B en eteau, C edric Le Caignec, and Albert David CHU Nantes, Service de G en etique M edicale, Nantes, France CHU Nantes, Service de Dermatologie, Nantes, France INSERM, UMR915, l’institut du thorax, Nantes, France CNRS, ERL3147, Nantes, France Universit e de Nantes, Nantes, France

Split hand/foot malformation with long-bone deficiency and BHLHA9 duplication: report of 13 new families.

Split hand/foot malformation (SHFM) with long‐bone deficiency (SHFLD, MIM#119100) is a rare condition characterized by SHFM associated with long‐bone malformation usually involving the tibia. Previous published data reported several unrelated patients with 17p13.3 duplication and SHFLD. Recently, the minimal critical region had been reduced, suggesting that BHLHA9 copy number gains are associated with this limb defect. Here, we report on 13 new families presenting with ectrodactyly and harboring a BHLHA9 duplication.

Prenatal diagnosis of 24 cases of microduplication 22q11.2: an investigation of phenotype‐genotype correlations

Microduplication 22q11.2 is primarily characterized by a highly variable clinical phenotype, which ranges from apparently normal or slightly dysmorphic features (in the presence or absence of learning disorders) to severe malformations with profound mental retardation. Hence, genetic counseling is particularly challenging when microduplication 22q11.2 is identified in a prenatal diagnosis. Here, we report on 24 prenatal cases of microduplication 22q11.2.

Le syndrome de Beckwith-Wiedemann : que faut-il rechercher en anténatal ? À propos d’une série de 14 cas

OBJECTIVES Beckwith-Wiedemann syndrome (BWS) is the most common overgrowth syndrome and has an incidence of 1/13,700. The majority of the cases are diagnosed after birth. Patients with BWS have an increased risk of neonatal hypoglycemia and embryonal tumors development in childhood. We wanted to identify the ultrasound signs that must alert physicians to prepare best perinatal management strategies. METHODS We conducted a retrospective study of a population of 14 cases of BWS diagnosed in perinatal period; four of them were detected prenatally by ultrasound. The anomalies signs described in prenatal were analyzed and compared with the clinical features of the postnatal period. RESULTS The major features reported were represented by macrosomia for 71.4% with an increase of abdominal circumference, and macroglossia for 78.6%. The minor features were various with 64% of visceromegaly (nephromegaly and/or hepatomegaly), 50% of hydramnios and for 80% of male children a genital anomaly (crytorchidism and/or hypospadias). CONCLUSION This study identified some prenatal ultrasound signs that should alert the clinician to the possibility of BWS. A genetic conseling, after confirmation by molecular diagnosis, could be proposed in a near future in prenatal, and could improve postnatal management strategies for these affected children at high postnatal risk.

RSPO2 inhibition of RNF43 and ZNRF3 governs limb development independently of LGR4/5/6

The four R-spondin secreted ligands (RSPO1–RSPO4) act via their cognate LGR4, LGR5 and LGR6 receptors to amplify WNT signalling1–3. Here we report an allelic series of recessive RSPO2 mutations in humans that cause tetra-amelia syndrome, which is characterized by lung aplasia and a total absence of the four limbs. Functional studies revealed impaired binding to the LGR4/5/6 receptors and the RNF43 and ZNRF3 transmembrane ligases, and reduced WNT potentiation, which correlated with allele severity. Unexpectedly, however, the triple and ubiquitous knockout of Lgr4, Lgr5 and Lgr6 in mice did not recapitulate the known Rspo2 or Rspo3 loss-of-function phenotypes. Moreover, endogenous depletion or addition of exogenous RSPO2 or RSPO3 in triple-knockout Lgr4/5/6 cells could still affect WNT responsiveness. Instead, we found that the concurrent deletion of rnf43 and znrf3 in Xenopus embryos was sufficient to trigger the outgrowth of supernumerary limbs. Our results establish that RSPO2, without the LGR4/5/6 receptors, serves as a direct antagonistic ligand to RNF43 and ZNRF3, which together constitute a master switch that governs limb specification. These findings have direct implications for regenerative medicine and WNT-associated cancers.Independently of the LGR4/5/6 receptors, RSPO2 acts as a direct antagonistic ligand to RNF43 and ZNRF3 during embryogenesis, and specifies the position and number of limbs that an embryo should form.

Two novel variants in CNTNAP1 in two siblings presenting with congenital hypotonia and hypomyelinating neuropathy

Homozygous frameshift variants in CNTNAP1 have recently been reported in patients with arthrogryposis and abnormal axon myelination. In two brothers with severe congenital hypotonia and foot deformities, we identified compound heterozygous variants in CNTNAP1, reporting the first causative missense variant, p.(Cys323Arg). Motor nerve conductions were markedly decreased. Nerve microscopical lesions confirmed a severe hypomyelinating process and showed loss of attachment sites of the myelin loops on the axons, which could be a characteristic of Caspr loss-of-function. We discuss the pathophysiology of the myelination process and we propose to consider this disorder as a congenital hypomyelinating neuropathy.